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/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.core.annotation;

import java.lang.annotation.Annotation;
import java.util.Map;

import org.springframework.lang.Nullable;
import org.springframework.util.ClassUtils;
import org.springframework.util.ConcurrentReferenceHashMap;

/**
 * General utility for determining the order of an object based on its type declaration.
 * Handles Spring's {@link Order} annotation as well as {@link javax.annotation.Priority}.
 *
 * @author Stephane Nicoll
 * @author Juergen Hoeller
 * @since 4.1
 * @see Order
 * @see javax.annotation.Priority
 */
@SuppressWarnings("unchecked")
public abstract class OrderUtils {

	/** Cache marker for a non-annotated Class. */
	private static final Object NOT_ANNOTATED = new Object();


	@Nullable
	private static Class priorityAnnotationType;

	static {
		try {
			priorityAnnotationType = (Class)
					ClassUtils.forName("javax.annotation.Priority", OrderUtils.class.getClassLoader());
		}
		catch (Throwable ex) {
			// javax.annotation.Priority not available
			priorityAnnotationType = null;
		}
	}


	/** Cache for @Order value (or NOT_ANNOTATED marker) per Class. */
	private static final Map, Object> orderCache = new ConcurrentReferenceHashMap<>(64);

	/** Cache for @Priority value (or NOT_ANNOTATED marker) per Class. */
	private static final Map, Object> priorityCache = new ConcurrentReferenceHashMap<>();


	/**
	 * Return the order on the specified {@code type}, or the specified
	 * default value if none can be found.
	 * 

Takes care of {@link Order @Order} and {@code @javax.annotation.Priority}. * @param type the type to handle * @return the priority value, or the specified default order if none can be found * @since 5.0 * @see #getPriority(Class) */ public static int getOrder(Class type, int defaultOrder) { Integer order = getOrder(type); return (order != null ? order : defaultOrder); } /** * Return the order on the specified {@code type}, or the specified * default value if none can be found. *

Takes care of {@link Order @Order} and {@code @javax.annotation.Priority}. * @param type the type to handle * @return the priority value, or the specified default order if none can be found * @see #getPriority(Class) */ @Nullable public static Integer getOrder(Class type, @Nullable Integer defaultOrder) { Integer order = getOrder(type); return (order != null ? order : defaultOrder); } /** * Return the order on the specified {@code type}. *

Takes care of {@link Order @Order} and {@code @javax.annotation.Priority}. * @param type the type to handle * @return the order value, or {@code null} if none can be found * @see #getPriority(Class) */ @Nullable public static Integer getOrder(Class type) { Object cached = orderCache.get(type); if (cached != null) { return (cached instanceof Integer ? (Integer) cached : null); } Order order = AnnotationUtils.findAnnotation(type, Order.class); Integer result; if (order != null) { result = order.value(); } else { result = getPriority(type); } orderCache.put(type, (result != null ? result : NOT_ANNOTATED)); return result; } /** * Return the value of the {@code javax.annotation.Priority} annotation * declared on the specified type, or {@code null} if none. * @param type the type to handle * @return the priority value if the annotation is declared, or {@code null} if none */ @Nullable public static Integer getPriority(Class type) { if (priorityAnnotationType == null) { return null; } Object cached = priorityCache.get(type); if (cached != null) { return (cached instanceof Integer ? (Integer) cached : null); } Annotation priority = AnnotationUtils.findAnnotation(type, priorityAnnotationType); Integer result = null; if (priority != null) { result = (Integer) AnnotationUtils.getValue(priority); } priorityCache.put(type, (result != null ? result : NOT_ANNOTATED)); return result; } }





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